Exhaust processor with variable tuning system

ABSTRACT

An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.

BACKGROUND AND SUMMARY

[0001] This disclosure relates to an engine exhaust processor, and inparticular, to an exhaust processor including a Helmholtz resonator.More particularly, this disclosure relates to an exhaust processor toattenuate noise associated with combustion product produced by theengine.

[0002] Noise in a vehicle exhaust system arises from acoustic waves thatare generated by the sudden release of exhaust gases from individualcylinders in a vehicle engine. These acoustic waves travel from theengine exhaust manifold through a pipe to a muffler or other resonatoron board the vehicle.

[0003] In order to dampen these acoustic waves to reduce the soundemitted by a vehicle, resonance chambers are provided in a muffler orother resonator to attenuate the acoustic waves. One type of resonancechamber is a Helmholtz resonator. A resonance chamber absorbs energyfrom the acoustic waves, which acts to silence somewhat the noiseemitted from the muffler. Each resonance chamber is designed to “tune”or “silence” acoustic waves of a certain frequency.

[0004] According to the present disclosure, an exhaust processorincludes an acoustic resonator and a resonator controller. The resonatorincludes a housing providing a static tuning volume and a tuning tubeextending into that static tuning volume. The tuning tube receivesengine combustion product. An outlet opening is formed in the tuningtube and arranged to lie in the static tuning volume and to place thestatic tuning volume in acoustic communication with acoustic wavesassociated with engine combustion product in the tuning tube.

[0005] The resonator controller functions to vary the size of the outletopening so that the tuning frequency of the resonator can be changed byincreasing or decreasing the size of the outlet opening. The resonatorcontroller includes an outlet opening size regulator and a regulatoroperator for moving the regulator over the outlet opening formed in thetuning tube as a function of one or more selected “engine parameters”(e.g., engine rpm) to change the size of the outlet opening.

[0006] In an illustrative embodiment, the outlet opening is defined by afield of perforations formed in the tuning tube and the resonatorcontroller includes a sleeve that is mounted to slide back and forth onthe tuning tube either to “open” more perforations in the field (toincrease the size of the outlet opening) or to “close” more perforationsin the field (to decrease the size of the outlet opening). It is withinthe scope of this disclosure to use the exhaust processor disclosedherein to attenuate noise associated with combustion product produced bya wide variety of engines (including motor vehicle engines).

[0007] In an illustrative embodiment, the resonator controller furtherincludes an engine mode detector that cooperates with the regulatoroperator to control movement of the sleeve (or other outlet opening sizeregulator) in a prescribed manner depending upon the “mode of operation”of the vehicle engine. Some engines have a variable mode of operating;for example, an eight-cylinder engine could be operated in four-, five-,or six-cylinder mode, depending on the “cylinder activation ordeactivation” algorithm established in the engine. Engine combustionproduct is characterized by an “acoustic signature” unique to each modeof operation.

[0008] In this embodiment, the engine mode is sensed by the engine modedetector and the regulator operator included in the resonator controlleris instructed to move the sleeve relative to the tuning tube to open andclose perforations in the field in accordance with a “predeterminedcriteria” established in advance for each mode of engine operation anddocumented in the regulator operator or elsewhere in the exhaustprocessor. Thus, using the engine mode-sensitive resonator controllerdisclosed herein, the tuning frequency adjustment system of the acousticresonator can be changed easily and automatically in a manner bestsuited to match the acoustic signature associated with each mode ofengine operation.

[0009] Additional features of the disclosure will become apparent tothose skilled in the art upon consideration of the following detaileddescription of illustrative embodiments exemplifying the best mode ofcarrying out the disclosure as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The detailed description particularly refers to the accompanyingfigures in which:

[0011]FIG. 1 is a diagrammatic view of an exhaust processor inaccordance with the present disclosure showing a variable resonatorconfigured to conduct combustion product exhausted by an engine througha tuning tube and a resonator controller that monitors an engineparameter (e.g., engine r.p.m.) and causes the size of the outletopening from the tuning tube into a static tuning volume to varycontinuously as a function of that engine parameter during engineoperation so that the “effective length” of the tuning tube coupled tothe static tuning volume is varied to attenuate noise associated withengine combustion product in accordance with a predetermined criteria;

[0012]FIG. 2 is a side elevation view of an illustrative exhaustprocessor of the type diagrammed in FIG. 1, with portions broken away,showing a variable resonator including a static tuning volume providedby an exhaust processor housing and a perforated tuning tube extendingthrough the housing and a resonator controller including an outletopening size regulator comprising a sleeve that can move back and forthon the perforated tuning tube to vary the number of tuning tubeperforations “open” to the static tuning volume provided in the housingaround the perforated tuning tube so as to vary the size of the tuningtube “outlet opening” and thus the effective length of the tuning tubeand a regulator operator comprising a motor, a sleeve mover, and amotion converter configured to reciprocate the sleeve mover in responseto rotation of a shaft included in the motor, and showing that thesleeve has been moved to a fully extended position exposing eight rowsof perforated openings;

[0013]FIG. 3 is a view similar to FIG. 2 showing that the sleeve hasbeen moved to a fully retracted position exposing one row of perforatedopenings;

[0014]FIG. 4 is a view similar to FIGS. 2 and 3 showing that the sleevehas been moved to a midway position to increase the effective length ofthe tuning tube by exposing four rows of perforated openings;

[0015]FIG. 5 is a view similar to FIG. 3 showing an illustrativeembodiment of a motion converter and a first illustrative embodiment ofa sleeve mover;

[0016]FIG. 6 is a view similar to FIG. 5 showing a second illustrativeembodiment of a sleeve mover;

[0017]FIG. 7 is a view similar to FIGS. 5 and 6 showing a thirdillustrative embodiment of a sleeve mover;

[0018]FIG. 8 is a view similar to FIG. 7 showing another illustrativeexhaust processor wherein an outlet end of a perforated tuning tubecarrying a movable sleeve is coupled to a low-frequency tuning tubecommunicating with a second static tuning volume located in the housing“alongside” an upstream first static tuning volume communicating withthe perforated tuning tube;

[0019]FIG. 9 is an enlarged perspective view of the low-frequency tuningtube shown in FIG. 8;

[0020]FIG. 10 is a view similar to FIG. 8 showing another illustrativeexhaust processor including a low-frequency tuning tube coupled to anoutlet end of a perforated tuning tube carrying a sleeve wherein theperforated tuning tube and the low-frequency tuning tube share a commonstatic tuning volume provided in the exhaust processor housing;

[0021]FIG. 11 is an enlarged perspective assembly view showing theoutlet end of the perforated tuning tube before it is inserted into aninlet end of the low-frequency tuning tube;

[0022]FIG. 12 is an enlarged sectional view taken along line 12-12 ofFIG. 10 showing the outlet end of the perforated tuning tube mounted inthe inlet end of the low-frequency tuning tube;

[0023]FIG. 13 is a side elevation view of another illustrative exhaustprocessor, with portions broken away, showing an exhaust processorhousing partitioned by a movable baffle to define first and secondstatic tuning volumes, a perforated tuning tube extending through thehousing and a central aperture formed in the movable baffle, a sleevecoupled to the baffle to move therewith back and forth on the perforatedtuning tube, and a sleeve mover coupled to the movable baffle;

[0024]FIG. 14 is a view similar to FIG. 13 showing use of the sleevemover to move the baffle in the housing to change the size of each ofthe first and second static tuning volumes and to move the sleeve on theperforated tuning tube so that fewer tuning tube perforations “open”into the upstream first static tuning volume and more tuning tubeperforations open into the downstream second static tuning volume;

[0025]FIG. 15 is an enlarged sectional view taken along line 15-15 ofFIG. 13 showing flow apertures formed in the movable baffle;

[0026]FIG. 16 is a view similar to FIG. 15 showing a movable bafflewithout any flow apertures;

[0027]FIG. 17 is a side elevation view of another illustrative exhaustprocessor, with portions broken away, showing a perforated inlet tube, aperforated outlet tube, and a sleeve mover adapted to move sleevesmounted for sliding movement on the perforated inlet and outlet tubes;

[0028]FIG. 18 is a view similar to FIG. 17 showing placement of theperforations in the outlet tube in a location different than that shownin FIG. 17;

[0029]FIG. 19 is a diagrammatic view of another exhaust processor inaccordance with the present disclosure showing a variable resonator anda resonator controller including an engine mode detector coupled to theengine and configured to detect the engine mode (e.g., 4, 5, 6, or 8cylinder operation) selected by a vehicle operator or apparatus toregulate operation of the resonator controller using the engineparameter in a manner suited to the selected engine mode;

[0030]FIG. 20 is a diagrammatic view of yet another exhaust processor inaccordance with the present disclosure showing a variable resonatorarranged to communicate with combustion product flowing through a flowconduit located in an exhaust processor housing; and

[0031]FIG. 21 is a side elevation view of an exhaust processor, withportions broken away, illustrative of the exhaust processor showndiagrammatically in FIG. 20.

DETAILED DESCRIPTION OF THE DRAWINGS

[0032] An exhaust processor 10 comprising a variable acoustic resonator12 and a resonator controller 14 functions to silence or quiet noiseassociated with combustion product generated by engine 16. As suggestedin FIG. 1, resonator 12 includes a tuning tube 18 provided with avariable size outlet opening 20 to communicate acoustic waves associatedwith engine combustion product admitted into tuning tube 18 throughinlet opening 22 to a Helmholtz resonance chamber established by statictuning volume 24. Resonator controller 14 functions to change the sizeof outlet opening 20 during operation of engine 16 by moving an outletopening size regulator 26 over outlet opening 20 in tuning tube 18. Thismovement of regulator 26 increases or decreases the size of outletopening 20 under the control of a regulator operator 28 that senses anengine parameter 30 (e.g., engine r.p.m.) of engine 16 and movesregulator 26 in response to real-time changes in engine parameter 30that occur during operation of engine 16 so as to vary the size ofoutlet opening 20 during engine operation to “tune” or “silence”acoustic waves associated with engine combustion product extant intuning tube 18. Tunable acoustic systems are disclosed in U.S. Pat. Nos.5,930,371and 4,539,947. Those disclosures are hereby incorporated byreference herein.

[0033] In an illustrative embodiment, a tuning tube 18 extends into astatic tuning volume 24 provided in a resonator housing 32 as shown, forexample, in FIGS. 2-4. Housing 32 includes first and second end walls34, 36 and a side wall 38 arranged to extend from first end wall 34 tosecond end wall 36. An inlet end of tuning tube 18 extends through anaperture 40 formed in first end wall 34 and an outlet end of tubing tube18 extends through an aperture 42 formed in second end wall 36. A fieldof perforations 44 arranged, for example, in longitudinally spaced-apartannular rows, is formed in tuning tube 18 to define outlet opening 20.Acoustic waves (not shown) associated with combustion product (notshown) in tuning tube 18 are communicated to static tuning volume 24 inhousing 32 via opened perforations 44 in the perforation field.Combustion product discharged from tuning tube 18 is dischargedtherefrom in direction 45 to a downstream destination.

[0034] A sleeve 46 formed to include a longitudinal passageway 48receiving tuning tube 18 therein is mounted for back-and-forth (orother) movement on tuning tube 18 in static tuning volume 24 to open andclose perforations 44 so as to increase or decrease the effective sizeof outlet opening 20. Regulator operator 28 comprises a sleeve mover 50coupled to sleeve 46 and a mover driver 52 coupled to sleeve mover 50.Mover driver 52 comprises, for example, a motor 54 and a motionconverter 56 for converting an output (e.g., rotary movement of a driveshaft) of motor 52 into reciprocating movement of sleeve mover 50. Inone embodiment, motion converter 56 is a rack-and-pinion mechanism ofthe type suggested diagrammatically in FIG. 5.

[0035] In operation, sleeve 46 can be moved by regulator operator 28 toopen a maximum number of perforations 44 (so as to maximize the size ofoutlet opening 20) as shown, for example, in FIG. 2 or close most ofperforations 44 (so as to minimize the size of outlet opening 20) asshown, for example, in FIG. 3. By leaving at least one perforation 44open (or uncovered by sleeve 46), acoustic waves associated with enginecombustion product in tuning tube 18 are transmitted into the statictuning volume 24 around tuning tube 18. Sleeve 46 is positioned to openeight annular rows of perforations 44 in FIG. 2, one annular row ofperforations 44 in FIG. 1, and four annular rows of perforations 44 inFIG. 4. It is within the scope of this disclosure to position sleeve 46relative to the field of perforations 44 so that movement of sleeve 46to the right (in FIG. 2) decreases the size of outlet opening 20.

[0036] Several illustrative examples of sleeve movers 50 are shown inFIGS. 5-7. These sleeve movers 50 are configured to cause sleeve 46 tomove back and forth on tuning tube 18 along an axis that is coextensivewith the central longitudinal axis 63 of tuning tube 18.

[0037] As shown in FIG. 5, sleeve mover 50′ comprises a guide rod 60mounted in a fixed position in housing 32 and a slidable collar 62coupled to sleeve 46 by a post 61 and mounted for sliding movement onguide rod 60 to cause sleeve 46 to move relative to tuning tube 18 alongan axis 63 parallel to a longitudinal axis 64 established by quick rod60. A push-pull rod 66 is coupled at one end to motion converter 54 andat another end to post 61. In the illustration in FIG. 5, guide rod 60is coupled at one end to first end wall 36 and is coupled at an oppositeend to second end wall 38. It is within the scope of this disclosure tocouple the ends or other portions of guide rod 60 to resonator housing32 or other structures associated with resonator housing 32 to establisha fixed position of guide rod 60 within housing 32.

[0038] As shown in FIG. 6, sleeve mover 50″ includes a post 61 coupledto a push-pull rod 66 which, in turn, is coupled to motion converter 54.Housing 32 further includes one or more interior baffles 68. Each baffle68 is positioned to lie inside housing 32 between first and second endwalls 36, 38. Baffle 68 is formed to include a first aperture 70receiving tubing tube 18 (and also sized to receive sleeve 46) thereinand a second aperture 72 receiving push-pull rod 66 therein to supportrod 66 for movement along a longitudinal central axis 73 parallel toaxis 63 of tuning tube 18. Each baffle 68 can be formed to include oneor more other apertures 74 as shown, for example, in FIG. 6 to adjustthe tuning frequency of the exhaust processor in a desired manner.

[0039] As shown in FIG. 7, sleeve mover 50″ includes a guide rod 60mounted at one end to one interior baffle 68 and at another end toanother interior baffle 68. The baffles 68 are positioned to lie inhousing 32 between first and second end walls 36, 38 and in spaced-apartrelation to one another. Push-pull rod 66 extends through aperture 72formed in one of baffles 68 and interconnects motion converter 54 andpost 61.

[0040] It is within the scope of this disclosure to couple alow-frequency tuning tube 76 to an outlet end 75 of tuning tube 18 asshown, for example, in FIG. 8. It is also within the scope of thisdisclosure to arrange a baffle 78 in housing 32 to partition theinterior region of housing 32 to define a static tuning volume 24′between first end wall 34 and baffle 78 and a low-frequency statictuning volume 80 between baffle 78 and second end wall 36. Baffle 78 iscoupled to side wall 38 to lie in a fixed position in the interiorregion of housing 32 in the embodiment shown in FIG. 8. Outlet end 75(or other portion) of tuning tube 18 is arranged to extend through acentral aperture 82 formed in baffle 78. Sleeve 46 is mounted on theportion of tuning tube 18 positioned to lie in static tuning volume 24′for movement relative to tuning tube 18 to open and close perforations44.

[0041] Low-frequency tuning tube 76 is formed to include a first inletopening 84 coupled in fluid communication to a second outlet opening 86formed in outlet end 75 of tuning tube 18 as shown, for example, in FIG.8. Low-frequency tuning tube 76 is also formed to include a first outletopening 85 arranged to lie in low-frequency static tuning volume 80 toplace low-frequency static tuning volume 80 in acoustic communicationwith acoustic waves associated with engine combustion product extant inlow-frequency tuning tube 76. This “coupling” of tuning tubes 18, 76allows engine combustion product flowing in a downstream direction 85through tuning tube 18 to empty into a passageway 87 formed inlow-frequency tuning tube 76 before it is discharged from tuning tube 76through a second outlet opening 88 formed in an outlet end 89 (of tuningtube 76) extending through an aperture 42 formed in second end wall 36as shown, for example, in FIG. 8.

[0042] Low-frequency tuning tube 76 comprises a large-diameter inletsection 90, a smaller diameter outlet section 89, and a necked-downconical transition section 93 interconnecting inlet and outlet sections90, 89 as shown, for example, in FIGS. 8 and 9. As shown in FIGS. 8 and9, inlet section 90 includes four circumferentially spaced-apartdepressions 91 that are sized and located to mate with an exteriorsurface of outlet end 75 of tuning tube 18 to couple low-frequencytuning tube 76 to tuning tube 18 in the manner specified herein. Inletsection 90 further includes four tunnel sections 92 configured to definefirst outlet openings 85 and arranged so that each tunnel section 92lies between a pair of adjacent depressions 91 as shown best forexample, in FIG. 9.

[0043] In operation, low-frequency static tuning volume 80 provides alow-frequency Helmholtz resonance chamber. Low-frequency acoustic wavesassociated with engine combustion product passing through passageway 87formed in tuning tube 76 are passed through first outlet openings 85also formed in tuning tube 76 and then tuned in low-frequency statictuning volume 80. At the same time, sleeve 46 located in static tuningvolume 24′ can be moved by regulator operator 28 to cause acoustic wavesof other frequency associated with engine combustion product passingthrough tuning tube 18 and its first outlet opening 20 defined by thefield of perforations 44 to be tuned in static volume chamber 40′.

[0044] It is within the scope of this disclosure to use tuning tubes 18and 76 in series without any interior baffle (such as baffle 78 shown inFIG. 8) as shown, for example, in FIG. 10 so that each of first outletopening 20 of tuning tube 18 and first outlet opening 85 oflow-frequency tuning tube 76 communicates with a single Helmholtzresonator chamber defined by static tuning volume 24 within housing 32.It is also within the scope of this disclosure to vary the size andshape of low-frequency tuning tube as can be seen in a comparison oftube 76 shown in FIGS. 8 and 9 and tube 76′ shown in FIGS. 10-12 toalter the low-frequency tuning capability of such a tube.

[0045] In an embodiment shown in FIGS. 13-16, an interior baffle 110 ismounted in the interior region of resonator housing 32 for movementrelative to side wall 38. Baffle 110 partitions the interior region ofhousing 32 to define a first static tuning volume 24′ between first endwall 34 and baffle 110 and a second static tuning volume 24″ betweenbaffle 110 and second end wall 36. In the illustrated embodiment, aportion of the first outlet opening 20 defined by the field ofperforations 44 is arranged to lie in each of the static tuning volumes24′ and 24″. The first and second static tuning volumes 24′ and 24″ varyin size as baffle 110 is moved back and forth inside housing 32 asshown, for example, in FIGS. 13 and 14. Baffle 110 can be formed toinclude vent apertures 112 as shown, for example, in FIGS. 13-15 orwithout vent apertures as shown, for example, in FIG. 16 to provide theexhaust processor designer with flexibility to tune certain frequencies.

[0046] Sleeve 46 is coupled to baffle 110 for movement therewithrelative to tuning tube 18 and side wall 38 as also shown in FIGS. 13and 14. Sleeve mover 50 extends into first static tuning volume 24′through an aperture formed in the housing 32 to move relative to housing32 to control movement of baffle 110 and sleeve 46 relative to thetuning tube 18 extending through sleeve 46 and a central aperture formedin baffle 110.

[0047] Referring now to embodiments shown in FIGS. 17 and 18, it will beseen that it is within the scope of this disclosure to cause a secondtube 118 to extend through an aperture 116 formed in second end wall 36into static tuning volume 24 and lie, for example, in spaced-apartparallel relation to tuning tube 18. In this embodiment, tuning tube 18is closed at its downstream end 116 so that all engine combustionproduct admitted into tuning tube 18 through inlet opening 22 isdischarged into static tuning volume 24. Second tube 118 is formed toinclude an inlet opening 120 arranged to lie in static tuning volume 24to allow engine combustion product therein to pass into a passageway 122formed in second tube 118. That passageway 122 has an outlet opening 124formed in outlet end 126 of second tube 126.

[0048] A second sleeve 146 is mounted for movement in static tuningvolume 24 alongside tube 118 as shown, for example, in FIG. 17 to varythe size of inlet opening 120 formed in second tube 118. Sleeve mover 50is coupled to each of sleeves 46, 146 to cause those sleeves 46, 146 tomove together as a unit relative to tuning tubes 18, 118 in response tooperation of motor 56 and motion converter 54. In the embodiment of FIG.17, the inlet openings 20, 120 are located so that movement of sleeves46, 146 in one direction minimize the size of both of those openings 20,120 whereas, in the embodiment of FIG. 18, the inlet openings 20, 120are located so that movement of sleeves 46, 146 in one directionminimizes the size of inlet opening 20 and maximizes the size of inletopening 120. It is also within the scope of this disclosure to omitsecond sleeve 146.

[0049] An exhaust processor 210 similar to exhaust processor 10 of FIG.1 is shown diagrammatically in FIG. 19. In this embodiment, engine 216is operable in five different modes, resonator controller 214 furthercomprises an engine mode detector 228 coupled to engine 216, andregulator operator 228 is configured to move outlet opening sizeregulator 26 based on real-time changes in engine parameter 30 (e.g.,engine r.p.m.) in accordance with a predetermined criteria establishedin advance for each mode of operation of engine 216.

[0050] A wide variety of power trains (e.g., solenoid-controlled valvetrains, camless engines, and cylinder deactivation technologies) posetuning challenges to exhaust system designers due to increasedcomplexity and cost associated with suitable tuning devices. Thechanging “operating mode” of an engine (e.g., an eight-cylinder enginecould operate in four-, five-, or six-cylinder mode depending on the“cylinder activation or deactivation” algorithm established in theengine) could require an exhaust system designer to tune all of theseindividual engine operating modes with, potentially, several tuningelements. Given the packaging and performance constraints of vehicles,consumers would welcome an exhaust silencer able to respond actively toengine operating modes in accordance with the present disclosure so asto minimize the need for passive silencers for each engine operatingmode. The resonator controller in accordance with the present disclosureis able to perform without increasing the restriction (back pressure) ofthe exhaust system and thus does not have a negative impact on enginepower output.

[0051] The displacement of outlet opening size regulator 26 relative tovariable size outlet opening 20 formed in tuning tube 18 is controlledvia a muffler control unit (MCU) incorporated in or linked to regulatoroperator 228. The electronic map stores data for regulator displacementversus the required tuning frequency.

[0052] In operation, regulator operator 228 moves regulator 26 relativeto tuning tube 18 as a function of one or more engine parameters (e.g.,engine r.p.m.) according to a predetermined criteria established foreach mode of operation of engine 216 based on the mode of operation ofengine 216 sensed by engine mode detector 228. This predeterminedcriteria is established in the MCU in a format suitable for use inregulator operator 228.

[0053] An exhaust processor 310 similar to exhaust processor 10 of FIG.1 is shown diagrammatically in FIG. 20 and illustratively in FIG. 21. Inthis embodiment, combustion product generated by engine 16 passes from acombustion product input 312 to a combustion product output 314 througha flow conduit 316. The inlet opening 22 of tuning tube 18 communicateswith engine combustion product extant in flow conduit 316.

[0054] In the illustrative embodiment shown in FIG. 21, an interiorbaffle 318 is mounted in the interior region of resonator housing 32′and static tuning volume 24 is located between baffle 218 and second endwall 36. Tuning tube 18 has an inlet end extending through an aperture320 formed in baffle 318 and sleeve 46 is movable in static tuningvolume 24 on tuning tube 18 to open and close perforations 44 formed intuning tube 18 and arranged to lie in static tuning volume 24. Flowconduit 316 includes an inlet section 322 bounded by first end wall 34,baffle 318, and a portion of side wall 38 located between first end wall34 and baffle 318. Flow conduit 316 also includes an outlet section 324coupled in fluid communication to inlet section 322 and defined by atube 326 extending through static tuning volume 24. Tube 326 has aninlet extending through an aperture 328 formed in baffle 318 to receiveengine combustion product from inlet section 322 and an outlet extendingthrough an aperture 330 formed in second end wall 36.

[0055] A single muffler in accordance with the present disclosure couldbe used for tuning various engine configurations simply by altering thecontrol logic. Such a muffler could also reduce or eliminate the needfor multiple “passive” tuning elements within an exhaust system because“one” tuning chamber could be used to silence multiple frequencies. Sucha muffler could be used for “camless” engines, where the engine couldpotentially switch to a four-, five-, six-, or eight-cylinder mode “onthe fly.” Such a muffler will potentially reduce muffler back pressurevia eliminating multiple tuning chambers. Such a muffler will minimizeexhaust system weight by “consolidating” multiple tuning elements intoone.

1. An exhaust processor comprising an acoustic resonator including ahousing formed to include a static tuning volume and a tuning tubepositioned to extend through an aperture formed in the housing into thestatic tuning volume, the tuning tube being formed to include an inletopening adapted to receive engine combustion product therein and a firstoutlet opening arranged to lie in the static tuning volume and to placethe static tuning volume in acoustic communication with acoustic wavesassociated with engine combustion product in the tuning tube, and aresonator controller including a regulator mounted for movement in thestatic tuning volume formed in the housing alongside the tuning tube tovary the size of the first outlet opening formed in the tuning tube. 2.The exhaust processor of claim 1, wherein the housing includes first andsecond end walls and a side wall arranged to extend from the first endwall to the second end wall to define the static tuning volumetherebetween and the first end wall is formed to include the aperturethrough which the tuning tube extends.
 3. The exhaust processor of claim2, wherein the second wall is formed to include an aperture, the tuningtube is arranged to extend through the aperture formed in the secondwall, and the regulator is mounted to move back and forth on the tuningtube in one of a first direction toward the first end wall to minimizethe size of the first outlet opening and a second direction toward thesecond end wall to maximize the size of the first outlet opening.
 4. Theexhaust processor of claim 2, wherein the resonator controller furtherincludes a mover driver located outside of the static tuning volume anda regulator mover arranged to extend through an aperture formed in oneof the first and second end walls and the regulator mover is coupled tothe mover driver and to the regulator to transmit motion generated bythe mover driver to the regulator to cause the regulator to movealongside the tuning tube to vary the size of the first outlet openingformed in the tuning tube.
 5. The exhaust processor of claim 1, whereinthe housing includes first and second end walls and a side wall arrangedto extend from the first end wall to the second end wall and theresonator controller further includes a mover driver located outside ofthe housing and a regulator mover arranged to extend through an apertureformed in the first end wall and the regulator mover is coupled to themover driver and to the regulator to transmit motion generated by themover driver to the regulator to cause the regulator to move alongsidethe tuning tube to vary the size of the first outlet opening formed inthe tuning tube.
 6. The exhaust processor of claim 5, wherein thehousing further includes a baffle coupled to the side wall andpositioned to lie inside the housing between the first and second endwalls and the regulator mover is arranged to extend through an apertureformed in the first baffle.
 7. The exhaust processor of claim 5, whereinthe housing further includes a baffle coupled to the side wall andpositioned to lie inside the housing between the first and second endwalls, the baffle is formed to include first and second apertures, thetuning tube is arranged to extend through the first aperture, theregulator is arranged to extend through the first aperture duringmovement of the regulator alongside the tuning tube, and the regulatormover is arranged to extend through the second aperture.
 8. The exhaustprocessor of claim 5, wherein the regulator operator further includes aguide rod mounted in a fixed position in the housing and a slidablecollar coupled to the regulator mover and mounted for sliding movementon the guide rod to cause the regulator to move relative to the tuningtube along an axis parallel to a longitudinal axis established by theguide rod.
 9. The exhaust processor of claim 8, wherein a first end ofthe guide rod is coupled to the first end wall and a second end of theguide rod is coupled to the second end wall.
 10. The exhaust processorof claim 8, wherein the housing further includes first and secondbaffles coupled to the side wall and positioned to lie inside thehousing and between the first and second end walls, a first end of theguide rod is coupled to the first baffle, a second end of the guide rodis coupled to the second baffle, and the regulator mover is arranged toextend through an aperture formed in the first baffle.
 11. The exhaustprocessor of claim 1, wherein a field of perforations is formed in thetuning tube to define the first outlet opening and the regulator is asleeve formed to include a longitudinal passageway extendingtherethrough and receiving the tuning tube therein.
 12. The exhaustprocessor of claim 11, wherein the housing further includes a bafflelocated in the static tuning volume and formed to include first andsecond apertures, the tuning tube is arranged to extend through thefirst aperture, the sleeve is arranged to extend through the firstaperture during movement of the sleeve alongside the tuning tube, andthe resonator controller further includes a resonator operator arrangedto extend into the static tuning volume through an aperture formed inthe housing to couple to the sleeve and to move relative to the housingto control movement of the sleeve relative to the tuning tube.
 13. Theexhaust processor of claim 1, wherein the housing includes first andsecond end walls, a side wall arranged to extend from the first end wallto the second end wall to define an interior region therebetween, and abaffle coupled to the side wall and arranged to partition the interiorregion to define the static tuning volume between the first end wall andthe baffle and a low-frequency static tuning volume between the baffleand the second end wall, the baffle is formed to include a centralaperture, the tuning tube is arranged to extend through the centralaperture and terminate at a second outlet opening positioned to lie inthe low-frequency static tuning volume, and further comprising alow-frequency tuning tube formed to include an inlet opening coupled tothe second outlet opening of the tuning tube to cause engine combustionproduct discharged from the tuning tube to pass into the low-frequencytuning tube, a first outlet opening arranged to lie in the low-frequencystatic tuning volume to place the low-frequency static tuning volume inacoustic communication with acoustic waves associated with enginecombustion product in the low-frequency tuning tube, and thelow-frequency tuning tube is arranged to extend through an apertureformed in the second end wall to conduct engine combustion product to adestination outside of the housing.
 14. The exhaust processor of claim1, wherein the tuning tube is formed to terminate at a second outletopening positioned to lie in the static tuning volume and furthercomprising a low-frequency tuning tube formed to include an inletopening coupled to the second outlet opening of the tuning tube to causeengine combustion product discharged from the tuning tube to pass intothe low-frequency tuning tube, a first outlet opening arranged to lie inthe static tuning volume to place the static tuning volume in acousticcommunication with acoustic waves associated with engine combustionproduct in the low-frequency tuning tube.
 15. The exhaust processor ofclaim 1, wherein the housing includes first and second end walls, a sidewall arranged to extend from the first end wall to the second end wallto define an interior region therebetween, and a baffle arranged topartition the interior region to define the static tuning volume betweenthe baffle and one of the first and second end walls and another statictuning volume between the baffle and the other of the first and secondend walls, the baffle is mounted for movement relative to the side wallto cause said static tuning volumes to vary in size as the baffle movesback and forth in the interior region formed in the housing, the baffleis formed to include a central aperture receiving the tuning tube andregulator therein, the regulator is coupled to the baffle for movementtherewith relative to the tuning tube and the side wall, and theresonator controller further includes a regulator operator arranged toextend into the static tuning volume through an aperture formed in thehousing to couple to the regulator and to move relative to the housingto control movement of the baffle and regulator relative to the tuningtube extending through the central aperture formed in the baffle. 16.The exhaust processor of claim 15, wherein a portion of the first outletopening formed in the tuning tube is arranged to lie in each of thestatic tuning volumes.
 17. The exhaust processor of claim 1, furthercomprising a second tube positioned to extend through a second apertureformed in the housing into the static tuning volume, the second tubebeing formed to include an inlet opening arranged to lie in the statictuning volume to allow engine combustion product discharge from thetuning tube into the static tuning volume through the first outletopening formed in the tuning tube to pass into a passageway formed inthe second tube, and wherein the resonator controller further includes asecond regulator mounted for movement in the static tuning volume formedin the housing alongside the second tube to vary the size of the inletopening formed in the second tube and a regulator operator arranged toextend into the static tuning volume and coupled to each of theregulator and the second regulator to control movement of saidregulators as a unit relative to the tuning tube and the second tube.18. An exhaust processor comprising a housing defining an interiorregion and having an inlet and an outlet, a flow conduit located in theinterior region of the housing to conduct engine combustion product fromthe inlet to the outlet, a static tuning volume located in the interiorregion of the housing and separate from the flow conduit, a tuning tubepositioned to lie in the interior region of the housing to extend intothe static tuning volume, the tuning tube being formed to include aninlet opening positioned to receive therein engine combustion productextant in the flow conduit and an outlet opening arranged to lie in thestatic tuning volume and to place the static tuning volume in acousticcommunication with acoustic waves associated with engine combustionproduct in the tuning tube, and a resonator controller including aregulator mounted for movement in the static tuning volume alongside thetuning tube to vary the size of the outlet opening formed in the tuningtube.
 19. The exhaust processor of claim 18, wherein the housingincludes first and second end walls, and a side wall arranged to extendfrom the first end wall to the second end wall to define the interiorregion therebetween and the flow conduit includes an inlet sectionbounded by the first end wall, the baffle, and a portion of the sidewall located between the first end wall and the baffle and an outletsection defined by a tube extending through the static tuning volume andhaving an inlet extending through an aperture formed in the baffle toreceive engine combustion product from the inlet section and an outletextending through an aperture formed in the second end wall.
 20. Anexhaust processor comprising an engine configured to have at least twomodes of operation and produce engine combustion product characterizedby an acoustic signature unique to each mode of operation, an acousticresonator including a static tuning volume, a tuning tube formed toinclude a passageway having an inlet opening arranged to receive enginecombustion product produced by the engine, and a first outlet openingformed in the tuning tube to place the static tuning volume in acousticcommunication with acoustic waves associated with engine combustionproduct in the tuning tube, and a resonator controller including aregulator mounted for movement alongside the tuning tube to vary thesize of the first outlet opening formed in the tuning tube, an enginemode detector coupled to the engine and configured to detect the mode ofoperation of the engine, and a regulator operator linked to the enginemode detector and the regulator to provide means for moving theregulator alongside the tuning tube to vary the size of the first outletopening in accordance with a first predetermined criteria based on aselected engine parameter communicated to the regulator operator whenthe engine is operated in a first mode of operation and with a secondpredetermined criteria based on the selected engine parametercommunicated to the regulator operator when the engine is operated in asecond mode of operation.